[nimonian]

_Exactly_.

Both the article and the parent comment treat "happens to have Kik account" as an independent discovery that affects our Bayesian inference.

No. The innocent was identified exactly _because_ they have a Kik account, so the conditional probability they have a Kik account is 1.

[jasonfarnon]

No. If the target of your "Bayesian inference" is whether the chain kik->gmail->ISP is reliable, then it isn't independent evidence. But that isn't the same as the target of inference in court, which is guilt or innocence, and obviously having kik is additional evidence for that. As I mentioned, the chain kik->gmail->ISP would not even be disputed in a run-of-the-mill accusation in the US, any more than DNA evidence gets scrutinized for lab mix-ups. You would need expensive attorneys and experts for that.